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Re: Thailand's strain of H5N1
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Re: Thailand's strain of H5N1
Thailand's two H5N1 strains 'not a threat'
By Tan Ee Lyn
Hong Kong - Recent outbreaks of H5N1 bird flu in Thailand were caused by two strains of the virus, but neither of them showed any significant mutation that would enable them to jump easily to people or spread with ease among humans.
Yong Poovorawan, a professor at Chulalongkorn University's Medical Faculty in Thailand, analysed two H5N1 samples taken from infected chickens in Thailand's central Pichit province and one taken from north-eastern Nakhon Phanom province last month.
The two samples from Pichit closely resembled a H5N1 strain that had circulated in Thailand in 2004 and 2005, his laboratory found.
</SPAN><!--pull quote --><TABLE cellSpacing=6 cellPadding=0 width=130 align=left border=0><TBODY><TR><TD class=pullquote>It is still difficult for humans to catch bird flu</TD></TR></TBODY></TABLE><!--pull quote end -->But the one from Nakhon Phanom was a new strain that had never been seen in Thailand and was most closely related to a strain that had been circulating since 2005 in southern China.
Genetic analyses showed all three samples had undergone slight mutations - which are typical of influenza A viruses that have circulated for some time - but the changes did not make them any more dangerous to people, Poovorawan said.
"The severity of the virus is the same," he told Reuters.
"There was no change in their receptor binding sites and there was no change in their resistance to (anti-viral) Tamiflu," he said, referring to two key traits of H5N1.
Scientists look at these traits when determining if there may may be changes in H5N1 that would enable it to jump more easily to people and spread easily among them.
It is still difficult for humans to catch bird flu because it has "receptor binding sites", which prefer to lock on to receptors in bird hosts, not humans.
Some experts believe it is when the H5N1's receptor binding site adapts to human hosts that it will transmit easily among people, and spark a pandemic that could kill millions.
Poovorawan said the genetic sequence of the H5N1 sample from Nakhon Phanom showed it was most closely related to a strain that has been circulating in China's eastern provinces of Zhejiang (2006) and Anhui (2005), Fujian (2005) in the southeast, and south-western Guangxi (2005).
"There are many ways to spread a virus from one place to another. Poultry, people, migratory birds," he said, but declined to speculate how the strain was introduced into Thailand.
The UN's Food and Agriculture Organisation said on Thursday the strain in Nakhon Phanom and neighbouring Laos appeared to have come from southern China and it called for stricter measures to prevent further spread of the disease in birds and poultry.
"Poultry trade across borders is continuing in Southeast and East Asia despite well-known risks," the organisation said.
On the Pichit strain, the FAO said it had "remained alive (in the past two-three years) in central Thailand in a reservoir of birds and poultry, most probably a mixture of backyard chickens, ducks and fighting cocks". A 17-year-old youth died in the outbreak.
The virus has spread to Europe, the Middle East and Africa and is known to have killed 139 people, according to the World Health Organisation. Indonesian officials also reported the death of a nine-year-old girl from the disease in West Java this week.
http://www.iol.co.za/index.php?set_i...5881341641B216Comment
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Re: Thailand's strain of H5N1
Ministry: Thai bird flu did not originate in China
By Liu Li (China Daily)
Updated: 2006-08-19 09:44
The Ministry of Agriculture denied on Friday a number of foreign reports that the recent outbreak of avian influenza in Thailand was due to a strain of the virus that probably came from southern China.
"This is groundless and irresponsible," sources with the ministry's press office told China Daily on Friday.
According to the current information held by the Chinese authorities, a verdict arrived at by the United Nations Food and Agriculture Organization (FAO) and the bird flu research and test centre of Thailand was arbitrary and based on the fact that the virus found in Thailand and Laos was similar to recent finds in southern China, the ministry's statement said.
The ministry has not found the full text of the test report by the FAO and the Thai centre and knew little about the test procedure, and origin and type of the examples used.
However some media reports quoted the FAO conclusion and correlated the outbreak in Thailand with southern China.
According to statistics provided by China's customs, the country has not exported any poultry products to Thailand or Laos since 2004 when China first reported a H5N1 outbreak in its poultry.
"Nakhon Phanom in Thailand and the Laotian capital of Vientiane, where the virus strain was detected, are both very far from the Chinese border," the ministry's statement said.
In conclusion, the ministry denied the possibility that the virus was transmitted through poultry trade across the borders, as was mentioned in several foreign reports.
The ministry emphasized that as the prevention and control abilities of different Asian countries varied, most reports were inconclusive and could not safely be used to detect new trends.
Also complicating the case is the fact that the virus can be transmitted by wild birds.
"So it is irresponsible to decide that the strain of virus detected in Thailand was from a certain country before having sufficient evidence," the statement said.
The ministry said that as a responsible country, China was ready to co-operate with all countries in to fight against the bird flu epidemic.
...when you have eliminated the impossible, whatever remains, however improbable, must be the truth. - Sherlock HolmesComment
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